Trimming mechanism for sewing-machines



A. H. DE VOE. TRIMMING MECHANISM FOR SEWlNG MACHINES. APPLICATION FILED JUNE 30, 1917.

1,336,825 Patented Apr. 13, 1920.

3 SHEET$SHEET 1.

INVENTOR t KM XML 3v I A ORNEY A. H. DE VOE.

TRIMMING MECHANISM FOR SEWING MACHINES.

APPLICATION FILED JUNE30| I917.

1,336,825. Patented p 13, 1920.

3 SHEETS-SHEET 2.

INVENTOR A ORNEY A. H. DE V'OE. TRIMMING MECHANISM FOR SEWING MACHINES. APPLICATION FILED JUNE 30. Hill.

I 1,336,825, Patented Apr. 13, 1920' O 3 SHEETS-SHEET 3- INVENTOR mfi z% ORNEY UNITED STATES PATENT oFFIoE;

ALBERT I-I. DE VOE, OF WESTFIELD, NEW JERSEY, ASSIGNOR TO THE SINGER MANU- FACTURING- COMPANY, A CORPORATION OF NEW JERSEY.

To all whom, it may concern:

Be it known that I, ALBERT H. DE Von, a citizen of the United States, residing at lVestfield, in the county of Union and State of New Jersey, have invented certain new and useful Improvements in Trimming Mechanisms for Sewing-Machines, of which the following is a specification, reference being had therein to. the accompanying drawings.

This invention relates to improvements 111 trimming mechanisms for sewing machines, and has for its principal object to provide a simple and efficient trimmer capable of being thrown into or out of operation at will. The invention has for a further object to support the trimming mechanism so as to render it capable of rapid and easy ad ustment to take up wear of the cutting elements and to position such" elements relative to the line of seam-formation.

In its preferred embodiment, this trimming mechanism is applied to a sewlng ma chine ofthesingle chain stitch type and is sustained by a support adapted to be secured to the sewing machine base in adjustable positions relative to the path of the needle. The trimming mechanism com- .prises a stationary blade carried by a block adjustably .secured upon the'support, and a movable blade, cooperating with the stationary blade and adjustably sustained by a can rier .secured upon .a rock-shaft .journaled in bearings formed in the support. Means tending to. retract the movable trimmerbladecarrier from its operative position are provided in the form of a torsional spring embracing the shaft and having itsopposite ends secured to the support and to the shaft respectively.

The movable trimmer-blade carrier is actuated from the main-shaft of the machine by means of an eccentric embraced by the strapof a pitman having pivotal connection with one arm of a bellcrank-lever fulcrumed atthe. opposite sides .ofa. slot. formed in the carrier. The other or free arm of the bell crank-lever is adapted to be engaged, in the operative position of the movable blade, by the notched extremity of an arm of a'springpressed latch-lever sustained by the carrier and of which another arm is positioned for convenient manipulation by an operator to disengage the latch from the arm of the bellcrank-lever referred to, whereupon the car- TRIMMING MECHANISM FOR SEWING-MACHINES.

Specification of Letters Patent. P t nted Apr. 13, 1920. Application filed June 30. 1917.

Serial No. 177.857.

rier is thrown out of operative position under the action of the torsional spring on the carrier-supporting shaft. The latch-lever is positioned to interlock with the free arm of the bellcrank-lever when the latter contacts with the rear wall of the slot in the trim mer-blade carrier, thereby facilitating and insuring the engagement of the arm by said of the same. Fig. 3 is a plan view of the sewing machine, omitting the overhanging arm, of-which the vertical standard is shown partly in section. Fig. fl is a detail plan of the support for the trnnming mechanism, and Fig. 5 is a detail view, partly in section,

of the preferred embodiment of the timming mechanism.

Referring to the drawings, the present improvement is shown as embodied in a sewing machine constructed with a base 1, from which rises the standard 2 having the usual overhanging bracketarm terminating in the head 3. Journaled in suitable bearings provided in the base 1 of the sewing machine is the mainshaft 4 provided with a belt-wheel 5 and a balance wheel 6. A crank 7 on the main-shaft 4 is connected. by a pitm an 8 with a lateral arm 9 on a rock-shaft 10 journaled in suitable bearings of the overhanging arm. The rock-shaft 10 imparts the usual vertical reciprocating movements to the needle-bar 11 carrying the needle 12. Mounted in the head 3 is the spring-pressed presscr-bar 13, to which the shank of an ordinary presserfoot 14L is secured. Cooperating beneath the work-support W withthe needle 12 in the formation of stitches is the looper 15 mounted to rotate with the main-shaft 4:.

The feeding mechanism comprises a feeddog 16 sustained by a feed-bar 17 pivotally supported on a rocking frame 18, fulcrumed by means of the pin 19 upon the base 1 and actuated from an eccentric on the mainshaft by a pitman 20 to impart feeding movements to the feed-clog. The feedbar 17 receives rising and falling movements from an eccentric on the main-shaft 4t and embraced by the strap 21 of a pin 22 which enters a socket provided in the feed-bar.

The trimming mechanism is carried by a support 23 sustained by the base 1 of the sewing machine, a rib 24 on the support entering a seat formed in the base. The support 23 is further sustained and guided, when adjusted, by the shoulders 25 and 26 provided on the base 1 and is adjustable from and toward the line of seam-formation, being secured in adjusted positions by the screws 27.

An arm 28 of the support 23 has secured thereto a block 29 adjustable transversely of the direction of feed, being guided by a rib 30 entering a transverse slot in the arm 28. The block 29 is cut away in its upper side to provide clearance for the feed-dog 16 and carries a stationary or ledger-blade 31 se cured thereto by screws 32.

Coiiperating with the stationary blade 31 is the movable trimmer-blade 33 secured by a screw 34 to a vibrating carrier-arm 35, fulcrumed by means of a rock-shaft 36 sustained in suitable bearings 37 of the support 23. The carrier 35 extends from its fulcrum point, which is laterally remote from the line of seam-formation, upwardly above the work-support andv thence outwardly, forwardly and downwardly to a point adjacent the path of the needle, thereby providing clearance for the work and obviating the necessity, with its attendant in conveniences, of diverting the severed material to opposite sides of the carrier. Surrounding the shaft 36 is a torsion-spring 38 of which one end enters an aperture in one of the bearings 37 and the other end enters an aperture in the adjusting nut 39. This spring tends to rock the shaft 36 and to throw the carrier 35 from operative to inoperative position.

The trimmer-blade carrier 35 is formed with a slot 40 of which the sides afford bearings for a pin 41, constituting a fulcrum for a rocking member in the form of a bellcrank-lever having an enlarged hub 42 and two arms 43 and 44. The arm 43 of the bellcrank-lever has secured thereto by a screw 45 a pivot-pin 46 entering apertures in the forked end of the pitman 47 having a strap 48 embracing an eccentric 49 on the main-shaft 4. In the operative position of the trimmer-blade carrier the free end of the arm 44 of the bellcrank-lever projects beyond the slot 40 and is adapted to be coupled with said carrier by engagement with a notch formed in one arm 50 of a latchlever or member, pivotally secured upon the carrier 35 and having the other arm 51 positioned substantially parallel with the carrier for convenient manipulation by an operator. A spring 52 is interposed between a stud 53 on the carrier 35 and the arm 50 of the latch-lever and tends to force the latter into latching position. The construction described permits the throwing of the carrier into and out of operation at will during the operation of the machine, both of the component members constituting the latch being sustained by the movable trimmer-blade carrier. When the carrier is thrown out of operative position, the bellcrank-lever rocks idly on its fulcrum, the carrier being restrained from vibration by means of the torsion-spring 38 which acts to hold the carrier against the forward portion of the overhanging bracket-arm of the machine.

As particularly shown in Fig. 5 of the drawings, the arm 44 contacts with the rear wall 54 of the slot 40 in the operative position of the trimmer-blade and forms an abutment which to some extent relieves the latch-lever of the thrust of the arm 44 of the bellcrank-lever and thus adds to the durability of the construction. This construction, furthermore, facilitates the latching of the arm 44, inasmuch as the latter can not pass beyond latching position when the carrier 35 is thrown manually from inoperative to operative position thereby determining the coupling relation of the arm 44 and the carrier.

Having thus set forth the nature of the invention, what I claim herein is 1. In a trimming mechanism for sewing machines, a movable trimmer-blade, a carrier for said blade, an actuating element, and means for coupling said carrier with said element including a disconnectible locking device of which the component members are mounted on said carrier.

2. In a trimming mechanism for sewing machines, a movable trimmer-blade carrier, an actuating element, a rocking member fulcrumed upon said carrier and actuated by said element, and means also supported by said carrier for locking said member and said carrier against relative movement.

3. In a trimming mechanism for sewing machines, in combination, a movable trimmer blade carrier, an actuating element, a lever fulcrumed upon said carrier and having a constant driving connection with said actuating element, means for coupling said lever and said carrier, and a stop for said lever provided on said carrier for partially relieving said coupling means of the thrust of said lever caused by said actuating element.

4. In a trimming mechanism for sewing machines, a movable blade, a carrier for said movable blade and formed with a slot of which one of the walls acts as an abutment, a member sustained by said carrier and positioned in said slot, an actuating element, means for connecting said member and said element, and means for coupling said carrier and said member.

5. A sewing machine trimming mechanism comprising a stationary blade, an adjustable support for said blade, a movable blade, a carrier for said movable blade fulcrumed on said support, a lever fulcrumed on said carrier, an actuating element, means for connecting the lever with said actuating element to idly move the lever upon its ful crum, and means for coupling said lever and said carrier.

6. In a trimming mechanism for sewing machines, a movable blade, a carrier for said blade, a lever fulcrumed on said carrier, an actuating element, means for connecting said lever and said actuating element to idly move said lever upon its fulcrum, means acting to hold said carrier against vibration during the idle movements of said lever, and means for coupling said lever and said carrier.

7 A trimming mechanism for sewing machines including, in combination, a needle and a cooperating loop-taker, a work-support, a stationary blade, a movable blade,

a carrier for said movable blade fulcrumed beneath the work-support at a point laterally remote from the line of seam-formation and extending from its fulcrum point upwardly above the work-support and laterally to a point adjacent the path of the needle, a lever fulcrumed on said carrier, an actuating element, operative connections between said lever and said actuating element, and means for coupling said lever and said carmen 8. In a trimming mechanism for sewing machines, a movable blade, a carrier for said movable blade, an actuating element, a member fulcrumed on said carrier having a constant driving connection with said actuating element, and a two-armed latchlever pivoted upon said carrier and adapted to couple said member with said carrier, said latch-lever extending along and substantially parallel with said carrier.

In testimony whereof, I have signed my name to this specification.

ALBERT H. DE VOE. 

